In order to realize the objective of reducing a rotary vibration during operation, a technology of controlling a torque of an electric motor caused by a waveform synthesis of a direct current (DC) frequency conversion electric motor is widely used in an air conditioner provided with a rotary compressor or a refrigerator provided with a reciprocating compressor. The technology of controlling the torque of the electric motor together with a rotary position of a rotor detects a variation of a shaft and performs the waveform synthesis of a frequency converter, so that the torque of the electric motor is similar to the eccentric shaft torque (called as shaft torque in following), and an angular velocity of the rotating rotor is stable.
The rotary vibration of the compressor may be reduced due to the technology of controlling. However the technology of controlling the torque of the electric motor cannot be used in an alternating current electric motor or an alternating current (AC) frequency conversion electric motor, an efficiency of the electric motor may be reduced due to the waveform synthesis. In addition, because of an increased cost and a technique difficulty, it is presumed that a worldwide penetration of the compressor using the technology of controlling the torque of the electric motor is below 5%.
In the related art, a compressing mechanism of the rotation compressor further has a spring to mitigate the rotation vibration, which mitigates a vibration transmission to a casing. In such method, it is difficult to connect the compressing mechanism to a suction tube and to align a stator with the rotor. In the related art, a disk-shaped weight is further provided, which increases an inertia three of the rotor and decreases the variation of the angular velocity of the eccentric shaft. The method requires a disk with a big outer diameter and a heavy weight, which is not realized, as a gap with respect to a coil of the electric motor cannot be ensured.